Browsing by Author "LEE, TY"

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CRACK SIZE IDENTIFICATION USING AN EXPANDED MODE METHOD
(1994-04-01)
KAM, TY
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LEE, TY
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交大名義發表
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機械工程學系
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National Chiao Tung University
An expanded mode method constructed based on the modal analysis method and an energy approach is presented for size identification of a crack with given location in a damaged structure. Measured natural frequencies and mode shapes of the structure with or without a crack are used to compute the strain energies of the structures subject to free vibration via a quasi-static approach. The two types of strain energy are then combined with the work required for the crack formation to construct the energy balance equation from which the size of the crack is evaluated through an iteration procedure. The theory of fracture mechanics is used to derive the work required for crack formation. Examples of the identification of crack sizes for a number of damaged beam structures are given to illustrate the applications of the proposed expanded mode method. Factors affecting the accuracy of crack size identification are investigated using a cracked cantilever beam as an example. The results show that the present method is promising for practical applications.
DETECTION OF CRACKS IN STRUCTURES USING MODAL TEST DATA
(1992-05-01)
KAM, TY
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LEE, TY
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交大名義發表
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機械工程學系
;
National Chiao Tung University
A nondestructive evaluation procedure is presented for identifying a crack in a structure using modal test data. The structure is discretized into a set of elements and the crack is assumed to be located within one of the elements. Measured vibration frequencies and mode shapes are used in an identification process to identify the cracked element based on a simple reduced stiffness model. Static deflection analyses of the structure with and without a crack are performed and a strain energy equilibrium equation is constructed for determining the size of the crack. The detection of a crack on a damaged beam is used to illustrate the applications of the proposed procedure. The present procedure is general and can be easily extended to complex structures with multiple cracks.
Reliability prediction of degraded structures via a statistical system identification approach
(1995)
KAM, TY
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LEE, TY
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機械工程學系
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Department of Mechanical Engineering